178 research outputs found
Servitization and enterprization in the construction industry:the case of a specialist subcontractor
The current economic climate and a continuing fall in output of the UK construction industry has led to falling prices and margins particularly affecting those lower down in the supply chain such as specialist subcontractors. Coen Ltd. is one such company based in the West Midlands. Faced with a need to up its game it has embarked on a business improvement programme concentrating on better operational efficiency, building stronger client relationships and delivering value added services. Lacking appropriate internal resources Coen has joined with Aston Business School in a 2 year ERDF sponsored project to fulfil the transformation programme. The paper will describe the evolution of product- service offerings in construction and link this with the work being carried out at Coen with Aston and outline the anticipated outcomes
Ruling Out Possible Secondary Stars to Exoplanet Host Stars Using the CHARA Array
Of the over 450 exoplanets known to date, more than 420 of them have been
discovered using radial velocity studies, a method that tells nothing about the
inclination of the planet's orbit. Because it is more likely that the companion
is a planetary-mass object in a moderate- to high-inclination orbit than a
low-mass stellar object in a nearly face-on orbit, the secondary bodies are
presumed to be planets. Interferometric observations allow us to inspect the
angular diameter fit residuals to calibrated visibilities in order to rule out
the possibility of a low-mass stellar companion in a very low-inclination
orbit. We used the Center for High Angular Resolution Astronomy (CHARA) Array
interferometer to observe 20 exoplanet host stars and considered five potential
secondary spectral types: G5 V, K0 V, K5 V, M0 V, and M5 V. If a secondary star
is present and is sufficiently bright, the effects of the added light will
appear in interferometric observations where the planet will not. All secondary
types could be eliminated from consideration for 7 host stars and no secondary
stars of any spectral type could be ruled out for 7 more. The remaining 6 host
stars showed a range of possible secondary types.Comment: Accepted for publication in the Astronomical Journa
The Search for Stellar Companions to Exoplanet Host Stars Using the CHARA Array
Most exoplanets have been discovered via radial velocity studies, which are
inherently insensitive to orbital inclination. Interferometric observations
will show evidence of a stellar companion if it sufficiently bright, regardless
of the inclination. Using the CHARA Array, we observed 22 exoplanet host stars
to search for stellar companions in low-inclination orbits that may be
masquerading as planetary systems. While no definitive stellar companions were
discovered, it was possible to rule out certain secondary spectral types for
each exoplanet system observed by studying the errors in the diameter fit to
calibrated visibilities and by searching for separated fringe packets.Comment: 26 pages, 5 tables, 8 figure
Antiviral inflammation during early pregnancy reduces placental and fetal growth trajectories
Many viruses are detrimental to pregnancy and negatively affect fetal growth and development. What is not well understood is how virus-induced inflammation impacts fetal-placental growth and developmental trajectories, particularly when inflammation occurs in early pregnancy during nascent placental and embryo development. To address this issue, we simulated a systemic virus exposure in early pregnant rats (gestational day 8.5) by administering the viral dsRNA mimic polyinosinic:polycytidylic acid (PolyI:C). Maternal exposure to PolyI:C induced a potent antiviral response and hypoxia in the early pregnant uterus, containing the primordial placenta and embryo. Maternal PolyI:C exposure was associated with decreased expression of the maternally imprinted genes Mest, Sfrp2, and Dlk1, which encode proteins critical for placental growth. Exposure of pregnant dams to PolyI:C during early pregnancy reduced fetal growth trajectories throughout gestation, concomitant with smaller placentas, and altered placental structure at midgestation. No detectable changes in placental hemodynamics were observed, as determined by ultrasound biomicroscopy. An antiviral response was not evident in rat trophoblast stem (TS) cells following exposure to PolyI:C, or to certain PolyI:C-induced cytokines including IL-6. However, TS cells expressed high levels of type I IFNR subunits (Ifnar1 and Ifnar2) and responded to IFN-α by increasing expression of IFN-stimulated genes and decreasing expression of genes associated with the TS stem state, including Mest. IFN-α also impaired the differentiation capacity of TS cells. These results suggest that an antiviral inflammatory response in the conceptus during early pregnancy impacts TS cell developmental potential and causes latent placental development and reduced fetal growth
Antiviral inflammation during early pregnancy reduces placental and fetal growth trajectories
Many viruses are detrimental to pregnancy and negatively affect fetal growth and development. What is not well understood is how virus-induced inflammation impacts fetal-placental growth and developmental trajectories, particularly when inflammation occurs in early pregnancy during nascent placental and embryo development. To address this issue, we simulated a systemic virus exposure in early pregnant rats (gestational day 8.5) by administering the viral dsRNA mimic polyinosinic:polycytidylic acid (PolyI:C). Maternal exposure to PolyI:C induced a potent antiviral response and hypoxia in the early pregnant uterus, containing the primordial placenta and embryo. Maternal PolyI:C exposure was associated with decreased expression of the maternally imprinted genes Mest, Sfrp2, and Dlk1, which encode proteins critical for placental growth. Exposure of pregnant dams to PolyI:C during early pregnancy reduced fetal growth trajectories throughout gestation, concomitant with smaller placentas, and altered placental structure at midgestation. No detectable changes in placental hemodynamics were observed, as determined by ultrasound biomicroscopy. An antiviral response was not evident in rat trophoblast stem (TS) cells following exposure to PolyI:C, or to certain PolyI:C-induced cytokines including IL-6. However, TS cells expressed high levels of type I IFNR subunits (Ifnar1 and Ifnar2) and responded to IFN-α by increasing expression of IFN-stimulated genes and decreasing expression of genes associated with the TS stem state, including Mest. IFN-α also impaired the differentiation capacity of TS cells. These results suggest that an antiviral inflammatory response in the conceptus during early pregnancy impacts TS cell developmental potential and causes latent placental development and reduced fetal growth
The CHARA Array Angular Diameter of HR 8799 Favors Planetary Masses for Its Imaged Companions
HR 8799 is an hF0 mA5 gamma Doradus, lambda Bootis, Vega-type star best known
for hosting four directly imaged candidate planetary companions. Using the
CHARA Array interferometer, we measure HR 8799's limb-darkened angular diameter
to be 0.342 +/- 0.008 mas; this is the smallest interferometrically measured
stellar diameter to date, with an error of only 2%. By combining our
measurement with the star's parallax and photometry from the literature, we
greatly improve upon previous estimates of its fundamental parameters,
including stellar radius (1.44 +/- 0.06 R_Sun), effective temperature (7193 +/-
87 K, consistent with F0), luminosity (5.05 +/- 0.29 L_Sun), and the extent of
the habitable zone (1.62 AU to 3.32 AU). These improved stellar properties
permit much more precise comparisons with stellar evolutionary models, from
which a mass and age can be determined, once the metallicity of the star is
known. Considering the observational properties of other lambda Bootis stars
and the indirect evidence for youth of HR 8799, we argue that the internal
abundance, and what we refer to as the effective abundance, is most likely
near-solar. Finally, using the Yonsei-Yale evolutionary models with uniformly
scaled solar-like abundances, we estimate HR 8799's mass and age considering
two possibilities: 1.516 +0.038/-0.024 M_Sun and 33 +7/-13 Myr if the star is
contracting toward the zero age main-sequence or 1.513 +0.023/-0.024 M_Sun and
90 +381/-50 Myr if it is expanding from it. This improved estimate of HR 8799's
age with realistic uncertainties provides the best constraints to date on the
masses of its orbiting companions, and strongly suggests they are indeed
planets. They nevertheless all appear to orbit well outside the habitable zone
of this young star.Comment: Accepted for publication in ApJ; 37 pages, 6 tables, 13 figure
Interleukin 15 modulates the effects of poly I:C maternal immune activation on offspring behaviour
Maternal infections during pregnancy are linked with an increased risk for disorders like Autism Spectrum Disorder and schizophrenia in the offspring. Although precise mechanisms are still unclear, clinical and preclinical evidence suggest a strong role for maternal immune activation (MIA) in the neurodevelopmental disruptions caused by maternal infection. Previously, studies using the Polyinosinic:Polycytidylic (Poly I:C) MIA preclinical model showed that cytokines like Interleukin 6 (Il6) are important mediators of MIA\u27s effects. In this study, we hypothesized that Il15 may similarly act as a mediator of Poly I:C MIA, given its role in the antiviral immune response. To test this hypothesis, we induced Poly I:C MIA at gestational day 9.5 in wildtype (WT) and Il15−/− rat dams and tested their offspring in adolescence and adulthood. Poly I:C MIA and Il15 knockout produced both independent and synergistic effects on offspring behaviour. Poly I:C MIA decreased startle reactivity in adult WT offspring but resulted in increased adolescent anxiety and decreased adult locomotor activity in Il15−/− offspring. In addition, Poly I:C MIA led to genotype-independent effects on locomotor activity and prepulse inhibition. Finally, we showed that Il15−/− offspring exhibit distinct phenotypes that were unrelated to Poly I:C MIA including altered startle reactivity, locomotion and signal transduction in the auditory brainstem. Overall, our findings indicate that the lack of Il15 can leave offspring either more or less susceptible to Poly I:C MIA, depending on the phenotype in question. Future studies should examine the contribution of fetal versus maternal Il15 in MIA to determine the precise developmental mechanisms underlying these changes
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